The limited communication and security capability of non-IP based networks, currently deployed in utility power grids, are crucial impediments to future smart grid deployments aimed at improving energy efficiency, resiliency against power flow disruptions, and reducing carbon emissions by incorporating renewable energy sources. Therefore, the power industry is undergoing a major network transformation by designing a new IP-based smart grid communication network with enhanced security and reliability.
One distinguishing aspect of the smart grid communication network is the large-scale deployment of sensors and smart meters which send periodic updates to the utility control center; for example, in Manhattan, N.Y., several million meters must be deployed to cover all customer households. The IP network being deployed is expected to transport the sensor data in a trustworthy (secure and reliable) fashion to the utility's control centers, where the data will be used to evaluate the grid state, and current electricity consumption. However, the sensors that generate the data are typically computationally constrained entities.
Sensor data collection is an integral part of smart grid communications. The data traffic generated from sensors or meters, which are typically located beyond utility security perimeters, is expected to be carried over a purpose-built utility network. The purpose-built utility network is isolated from the highly critical SCADA-based communication network. It is also isolated from the public Internet because of the significant security and availability issues that are encountered when utility data traffic is multiplexed with Internet data traffic.
The general characteristics of smart grid sensor data can be described as follows. First, data is carried over semi-permanent security and transport associations between sensors and utility side servers. Second, on the purpose-built utility network, data toward utility (north-bound data), such as meter readings, is periodically collected; in contrast, data originating from the utility (south-bound data), such as management information, is relatively rare. This implies that north-bound data would dominate network resource consumption, as compared with south-bound data. Third, north-bound data must be delivered in a reliable and timely fashion for precise estimation of instability induced conditions like a large mismatch between actual electricity usage and electricity supply based on day-ahead demand prediction. Comparatively, south-bound data to sensors or meters is not critical for reliable and timely delivery, since this information can be easily overridden by new data. Fourth, secure communication ensuring data credibility is necessary for safe power grid operations. We note that security requirements do not need to be symmetric. For example, authentication is mandatory for delivering the southbound electricity price information, but there is no requirement for confidentiality. In contrast, for the north bound metered data, both authentication and confidentiality are critical. Lastly, field sensors are unlikely to have a full set of operating systems and protocol stacks due to limited computation resources, while utility-side servers have plentiful computing resources to deal with the significant amount of data received from the large number of deployed sensors. For example, the TI MSP 430 microcontroller series adopted in many sensor hardware platforms feature 2-18 KB RAM, 1-256 KB EPROM, and 8-16 MHz CPU: a subset of OS and protocol features can be installed for the platforms; however, due to lack of storage space, data has to be delivered to servers in a utility network. To the best of the inventors' knowledge, there is no published protocol that accommodates above data transport requirements in a scalable and lightweight manner.